Do you use `return`

[Dason]

When you write functions do you include a `return` statement? It isn't necessary in most cases since R will return the last evaluated expression as what it returns when it reaches the end of the function. I know some people feel passionately that since it isn't necessary that it's misguided and introduces clutter. Some people think it provides clarity. What are your opinions on include return. Here are some examples for either

Using returns:

monitor_object <- function(object_name, FUN = dim){
    
    # Get
    fun_name <- deparse(substitute(FUN))
    print(fun_name)
    object_dim <- NULL
    if(exists(object_name)){
        object_output <- FUN(get(object_name))
    }
    
    callback_function <- function(...){
        new_output <- NULL
        if(exists(object_name)){
            new_output <- FUN(get(object_name))
        }
        if(!identical(new_output, object_output)){
            
            
            msg <- paste0(object_name, " changed. Summary function: ", fun_name, 
                         "\nOld output: ", paste(object_output, collapse = " "),
                         "\nNew output: ", paste(new_output, collapse = " "))
            object_output <<- new_output
            message(msg)
        }
        return(TRUE)
    }
    
    return(callback_function)
}

without returns:

monitor_object <- function(object_name, FUN = dim){
    
    # Get
    fun_name <- deparse(substitute(FUN))
    print(fun_name)
    object_dim <- NULL
    if(exists(object_name)){
        object_output <- FUN(get(object_name))
    }
    
    callback_function <- function(...){
        new_output <- NULL
        if(exists(object_name)){
            new_output <- FUN(get(object_name))
        }
        if(!identical(new_output, object_output)){
            
            
            msg <- paste0(object_name, " changed. Summary function: ", fun_name, 
                         "\nOld output: ", paste(object_output, collapse = " "),
                         "\nNew output: ", paste(new_output, collapse = " "))
            object_output <<- new_output
            message(msg)
        }
        TRUE
    }
    
    callback_function
}

 

[consuli]

Do not understand why C is releveant here.

However, I include return() most of the time.

 

[Dason]

Do not understand why C is releveant here.

Are you saying that because the code says "C-like"? There isn't an option for R but in terms of syntax highlighting I think the best you could describe R as with the options given is "C-like" since R does use a lot of similar keywords.

 

[GretaGarbo]

Or does the C means Code?

 

[Dason]

Or does the C means Code?

Nope

 

[trinker]

I use it in an if statement to keep it one line rather than an else

 

[Dason]

I use it in an if statement to keep it one line rather than an else

I'm not sure exactly what you mean. Can you give an example? And is that the only case that you use it?

 

[trinker]

I'm not sure exactly what you mean. Can you give an example? And is that the only case that you use it?

fun <- function(x, ...){

    if (x < 5) return('Low')

    'High'
}

fun(3)
## [1] "Low"

fun(8)
## [1] "High"

 

[hlsmith]

I use whatever the source code I am copying used.

 

[Dason]

What about

> f <- function(x, ...){if(x < 5) "Low" else "High"}
> f(3)
[1] "Low"
> f(7)
[1] "High"

 

[GretaGarbo]

Nope

Now, it means "Code:" (e.g. trinkers last post)

 

[Dason]

If you don't specify a language then it just defaults to "Code". Specifying a language will do things like give you some syntax highlighting and give some indication which language the code is. There isn't an "R" option but the syntax of R is similar enough to C that the option "C-like" gives some appropriate syntax highlighting.

 

[trinker]

What about

> f <- function(x, ...){if(x < 5) "Low" else "High"}
> f(3)
[1] "Low"
> f(7)
[1] "High"

Yeah but to me the return is more readable. Plus they can get nested. There may be 3-5 of these if() return() lines in there. It helps to avoid a bunch of nested if/elses.

 

[trinker]

@Dason Yihui uses return like I do : https://yihui.name/en/2018/01/stop-early/